Condition indicating instrument



April 8, 1941. W. FRYM'OYER 2,237,593

CONDITION INDICATING INSTRUMENT Filed Oct. 5, 1938 INVENTOR. Webser W[5- mo e1- BY 1 A QRNEYS Patented Apr. 8, 1941 UNITED STATES PATENTOFFICE CONDITION INDICATING INSTRUMENT Webster W. Frymoyer, Foxboro,Masa, assignor to The Foxboro Oompl y, Foxboro, Mass., a corporation ofMassachusetts Application October 5, 1938, Serial No. 233,350

' 3 Claims. (01. 73-339) ing either at the instrument or at some pointremoved.

It is among the objects of this invention to provide an outdoortemperature indicating device which is characterized by simplicity.sturdi ness and dependability-.' A further object is to provide a deviceof the above nature which can cope with varied weather conditions andaccurately indicate wide fluctuations in atmospheric conditions overextended periods of time without the necessity of attention. Otherobjects will be in part apparent and in part pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements, and arrangements of parts as will beexemplified in the structure to be hereinafter described and the scopeof the application of which will be indicated in the following claims.

In the drawing wherein there is shown one o the various possibleembodiments of this invention,

The figure is a diagrammatic perspective view of a temperatureindicating instrument which embodies the invention.

To preface the description of the invention and thereby clarify certainaspects thereof, it might be noted that large outdoor indicatinginstruments such as thermometers, for example, are generally inaccuratein their indications and undependable in so far as extended andunattended operation is concerned. Instruments of this type are oftenlocated in isolated or inaccessible spots where they are subjected toall sorts of weather conditions and temperature variations. In many ofthese instruments inaccuracies inevitably result through expansion orcontraction of operating parts from temperature changes. Otherscanothers, are overcome by the instrument now to be described. a

For illustrative purposes, the instrument will be described as athermometer.

Generally speaking; and with reference to the figure, the instrumentcomprises a pointer-operating mechanism or clock movement generallyindicated at 10 which swings a large pointer ll of a size readilyvisible from a distance or from a passing automobile, for example. Thispointer swings over a graduated dial (not shown) to indicate a conditionas interpreted by a conditionresponsive device, such as a fluid filledbulb l3, for example. Movement l0 also operates a small pointer l2located at the rear of the instrument.

Bulb l3 may be of any suitable type and is connected to a helical tubeIt by a capillary l5 housed in a preferably flexible cable l6, whichalso houses another capillary I'I connected to a compensating helicaltube l8. The right-hard end l8a. of tube I8 is anchored and its free endi8b is connected to one end of a rigid strap [9 whose other end isconnected to a shaft 20. The other end of shaft 20 carries an arm 2| towhich one end of a link 22 is connected. The other end of link 22 isattached to an arm 23 secured to the right-hand end a of tube 14, whoseother end Mb is operatively connected to an arm 23a which carries oneend of a link 24. Preferably capillary 15 includes a length iia coiledabout end Na of tube H for a purpose described below.

As noted, bulb I3 is filled with temperature responsive fluid whichexpands and contracts upon rise and fall of temperature, respectively.Capillary I1 is similarly filled. Thus upon a change, an increase forexample, in temperature, the fluid in bulb l3 increases the pressurewithin helix ll, causing the helix to move arm 23 clockwise, as shown inthe drawing. This interpretive action of helix i4 and arm 23 may beinaccurate, however, if it is not corrected for expansion of thetemperature of the capillary I5 and helix H. To this end compensatingtube 18 and capillary I! are provided. Expansion of the fluid incapillary II or helix [8 increases the pressure in helix l8 to cause itto move counterclockwise. This movement is translated by arm 2| and link22 to arm 23 which accordingly swings counterclockwise upon thetemperature rise to modify the setting of tube 23 and correct its actionto an accurate interpretation of the temperature change. Modification ofthe setting of helix I4 is not resisted by the attachment thereto ofcapillary 15 because of thecoiled length lia of the capillary.

It now appears that a temperature variation results in movement of link24 to the right or left as the temperature rises or falls, and thismovement is the true interpretation of the temperature change. The freeend of link is accordingly accurately positioned in accordance with thetemperature as measured by the bulb.

The left-handend of link 2! is connected to a rotary switch generallyindicated at II, the link degrees per minute.

being directly connected to an arm 25 secured to and rotatable with .apair of spaced discs 26 and 21 fastened to a shaft 28 preferablysubstantially frictioniessly mounted in suitable bear-. ings (notshown), Discs 25 and 2'! carry contact plates 29 and 30 each of which ismounted on an insulating sleeve (not shown) carried by shaft 28. Theplates are electrically connected in any suitable manner, Plates 29 and3d are positioned to engage respectively contactarms 31 and 32 mountedon a stud 33 between insulators at, as and 36 also on the stud, the studbeing secured to a bracket 37 which is pivotally mounted in suitablebearings (not shown)- coaxially with shaft 28. Stud 33 also carries apair of terminal arms 38 and 39 respectively connected electr cally tocontact arms 3! and 32.

Thus movement of link 26 in one direction or the other moves contactplates 29 and 3@ toward or away from contact arms 3! and 32 which, inturn, are movable toward and away from the contact plates by virtue ofthe pivotal mounting of bracket 3'5.

The free end 31a of bracket 3'! is connected to the lower end of a linkM whose upper end is adjustably fastened to the free end of an arm 32secured to and rotatable with a gear 53 rotatably mounted on the housingof pointer-operating mechanism lfl. Gear 63 is driven by a train ofreduction gears comprising gears 54 and 55 mountedon a shaft 36, gears4i! and 48 mounted on a shaft t9 and gear 50 mounted on a shaft i drivenby mechanism it. Preferably these gears are cut to afford a substantialreduction between gears 50 and 33.

ireferably mechanism iii comprises an electric clock movement ofstandard construction such asmight be employed for a tower clock or thelike. Accordingly. movement it includes a shaft 52 which carries pointerH, this shaft being that which would carry the hour hand of said clockand accordingly capable of moving onehalf of an angular degree perminute. Shaft 5i is that which would carry the minute hand of a clock,and hence is capable of moving six radial Movement 50 includes areversible driving motor generally indicated at 53 which drives a shaft56 carrying a gear 550. which meshes with a gear 55 which in turn mesheswith a drive gear 56 to drive movement iii. Preferably gear'55 ismounted on a lever 51 pivoted at 53 on the casing of movement it. Lever51 carries the gear 55 so that clockwise movement of lever 57 unmeshesears 5% and 56 and disconnects the drive of movement 80 to permit manualadjustment thereof by a knurled knob 68. A spring as biases lever 57counterclockwise to maintain gears 55, 55 and 56 in mesh.

Reversible motor 53 includes a rotor 6| which drives shaft 56 andaccordingly movement Hi.

solenoid coil 12 of a solenoid, generally indicated at 6 1, to a line $5in turn connected to oneend of the secondary coil 68 of a step-downtransformer generally indicated at M, the primary coil 69 of which isconnected across power lines and H. The other side of secondary 68 isconnected to line 63 by a line 68. Thus when contact plates 29 and allof switch 40 engage contact arms at and 22 a circuit is closed toenergize coil '52 of solenoid at, this circuit comprising plate 29,contact 3!, terminal 38, line 52, solenoid coil 72, line 65, secondarycoil 66, line 68, line $3, terminal 39, contact 32 and plate 30, back toplate 29. This circuit will hereinafter be designated circuit A?Solenoid includes a movable core '53 connected to a rod 76 which carriesa pair of contact bridges i5 and is. A line H, including a pair ofspaced contacts 78 and it connects line 52 with a line 30 and a line 8!respectively connected to a pair of terminals t2 and d3. Terminals 82and 83 are engaged alternately by pivoted contact arms at and 85 whichare operated by a timing mechanism generally indicated at 88 and'described in detail below. Contact arms 86 and 85 are respectivelyconnected to. line 63 by lines 88 and 87. Therefore, when bridge 15engages contacts i8 and 19, when either of terminals 82 or 83 isengaged, line H and accordingly line at is in circuit with line 55through solenoid 66. The circuit connecting lines 68 and 66 comprising,solenoid coil 52, line ll, contacts '38 and i9, bridge i5, lines or 8!,terminals 82 or 83, arms 36 or 35 and lines 8% or 87 will hereinafter bedesignated circuit B," and is a holdover circuit for the solenoid. Itmight here be noted that both circuits A and B are control or lowvoltage circuits energized through secondary 5b of transformer 61.

As noted above arms 86 and are operated by timing device as whichcomprises preferably a constantly running electric motor 85 which drivesa shaft 89 through a train of reduction gears 90 which illustrativelyrotate shaft 8% at one R. P. M. A pair of spaced cams 3i and 92' aremounted on shaft 89 and their surfaces include drops 9m and QZa-whichcoact with followers 93 and 94 on arms 86 and 85 to actuate the arms.Cams 9! and Q2 are so designed and arranged that either arm 85 isengaging terminal 82 or arm 85 is engaging terminal 33 except for ashort period, e. g. one second, when neither arm is engaging eitherterminal. Drop 82a hasslight precedence over drop em in the direction ofcam rotation; hence Just after follower 93 has dropped, and thus brokencontact between arm 88 and terminal 82, follower 96 is at the top of itsrise just ahead of drop am at which time contact between arm 85 andterminal 83 is also broken. Thus, for a moment neither of terminals 82or 83 is engaged and accordingly circuit B is broken.

As noted above, circuit "3 is a hold-overchcuit for solenoid 65. Thuswhen circuit "A" has been closed by rotary switch so as described above,solenoid 6:3 is energized and bridge i5- closes circuit "3 by engagingcontacts 718 and 19. The closing of circuit "13 maintains the energization of solenoid sauntil both terminals 92 and 83 are disengagedfrom arms 86 and 95. If circuit A" is not energized at this time throughswitch it no current can flow through the solenoid and its core 53 fallsto disengage bridge 75 w from contacts EB and is. When this happensengagement of terminals $2 or 88 by arms-8ft or 85 is ineffective toenergize the solenoid.

As noted above, movement lfi includes a reversible motor 53. This motorhas a forward field winding and a reverse field winding 95 respectivelyconnected to lines 97 and 98 which respectively include spaced contacts99, lot and 'ldl,

I92. Contacts 99 and ID! are connected by a line "Hi3, and a line lotconnects contact ml with power line H. When solencnd 56 is energized asand I to make a circuit hereinafter designated, circuit 0" comprisingpower line 1|, line I04, contact IOI, line I03, contact 99, bridge I5,contact I00, line 91, forward winding 95, a neutral line I05, aconnecting line I06, and power line 10. When solenoid 64 is unenergizedbridge 16 connects contacts |0| and |02 to make a circuit hereinafterdesignated circuit D comprising power line H, line I04, contact IOI,bridge 16, contact I02, line 98, reverse motor winding 96, line I06 andpower line 10. Thus it appears that circuits "0 and D are power circuitsunder the control of control circuits A and B.- According to which ofwindings 95 and 90 is energized, movement I0 is operated in onedirection or the other to swing pointers II and I2 clockwise orcounterclockwise, and as one or the other of the windings is alwaysenergized, motor 53 is always running in one direction or the other.

In operation, and assuming a drop in temperature, the fluid in bulb I3contracts to decrease the pressure in helix l4. This results in aninterpretive counterclockwise movement of arm 23a. Accordingly, link 24and arm 25 move to the left and rotate discs 25 and 21 to engage plates29 and 30 with contacts 3| and 32 respectively. This completes circuit Aand energizes solenoid I54 causing its core 13 to rise. Contacts 13 and19 are thus connected by bridge (establishing circuit B) and contacts 99and I00 are connected by bridge 16 (establishing circuit C"), toenergize forward winding 95 of motor 53.

If the-temperature continues to drop, link 24 and accordingly plates 29and 30 will continue to move to the left to maintain contact withcontacts 3| and 32. As long as this contact is maintained, circuit A andsolenoid 64 remain energized to maintain the energization of forwardwinding 95 of motor 53. During this operation, however, gears 50-43 aremoving link 4| downwardly, tending to break the contact between contacts29 and 30. Therefore, when the tem perature stops falling and plates 29and 30 reach a position which accurately indicates the temperature, theplates move no farther to the left.

, Contact arms 3| and 32, however, continue their counterclockwisemovement with the result that contact in the rotary switch 40. iseventually broken to de-energize circuit A and solenoid 34. If solenoidholdover circuit 3" is energized at the instant this break occurs,through the operation of timing device 33 counterclockwise movement ofcontact arm 3| and 32 continues for a short period until circuit B isbroken by the timing device. When this circuit is broken, bridge 15falls to make circuit D and energize reverse winding 96 of motor 53.Reversal of the motor accordingly causes upward movement of link 4| andclockwise movement of contacts 3| and 32 toward the now stationaryplates 29 and- 30. Because of the large reduction afforded by gears.5043, the movement of contacts 3| and 32 is relatively slow, andaccordingly they do not move far from plates 29 and 30. If thetemperature remains constant, there is, of course, no further movementof plates 29 and 30, and therefore contacts 3| and 32 move repeatedly(once a minute) 'into' and out of engagement with the plates through thealternate making and breaking of motor circuits C'and D, by theenergization and de-energization of solenoid 64 by rotary switch 40 andtiming device 89. 'The timing of the apparatus is such, however, thatthis alternate forward and reverse'movement of the various parts isrelatively minute and has but 75 little effect in changing the positionof pointer II. This relatively slow overshooting artificially producedprevents the switch 40 and the bridges l5 and 16 from going on and offfaster than once a minute, and so prevents their excessive wear without,however, introducing objectionable inaccuracies into the instrument.

It will now appear that contact arms 3| and 32 closely follow plates 29and 30, as these plates move to different positions in accordance withchanges in temperature. If the temperature rises, plates 29 and 30 movesteadily clockwise until they reach a position in accordance with theultimate temperature value. During this movement, contacts 3| and 32follow the plates because of the energization of reverse motor winding96, this winding being energized by circuit D which is complete as longas circuit A is broken.

It may now be seen that circuit A is intermittently energized toestablish circuit B which is periodically broken through the operationof timing device 86, and these two circuits coaot to make and breakmotor circuits C and D alternately. Hence motor 53 is always operatingin one direction or the other and accordingly switch contacts 3| and 32are always moving either toward or away from switch plates 29 and 30;also pointers II and I2 are constantly moving in one direction or theother. Because of the large reduction afforded by gear train 43-50 andbecause of the action of movement I0, the movement of pointer II andswitch contacts 3| and 32 is slow. This results in an accurateindication of temperature by pointer II as interpreted by the correctedmovement of helical tube I4 in response to bulb I3.

Thus a temperature responsive element (bulb I3) controls the position ofan agent (rotary switch 40) which in turn affects the operation ofindicating mechanism (movement I0 and pointer ill to effect an accurateindication of temperature values.

Accordingly Ihave provided a condition indicating instrument whichattains the several above-noted objects in a thoroughly practical and Iefficient manner.

As many possible embodiments may be made of the above invention and asmany changes, might be made in the embodiment above set forth, it is tobe understood that all matter hereinbefore set forth or shown in theaccompanying drawing is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. An instrument of the character described comprising, in combination,a switch having cooperating contacts movable to engaged and disengagedpositions, means responsive to temperature variations for moving some ofsaid contactsrelative to the others, means for visibly indicatingtemperature variations, operating means for said indicating meansincluding a reversible electric motor, an electric circuit for saidswitch, a solenoid connected to said circuit, a plurality of electriccircuits for said reversible motor and alternately'energizable tooperate said motor in opposite directions, means associated with saidsolenoid for completing said motor circuits alternately, means driven bysaid operating mechanism for moving the other of said switch contactsrelative to the first-mentioned switch contacts whereby when saidcontacts are in their disengaged position said solenoid is de-energizedto establish one of said motor circuits and whereby when said switchcontacts are engaged said solenoid is energized to establish another ofsaid motor circuits, and means for maintaining said solenoid inenergized condition for a predetermined period of time regardless of theoperative condition of said switch.

2. In a condition indicating instrument having a large pointer and acorresponding index adapted to be visible from a substantial distance,in combination, a reversible electric motor for operating said pointer,a switch having relatively movable contacts, condition responsive meansconnected to relatively move said contacts in accordance with variationsin the values of the condition, meansconnecting said motor to-saidswitch to relatively move said contacts in opposite sense, a controlcircuit controlled by said switch, a pair of power circuits forenergizing said motor to run in either of its two directions, meansunder control of said control circuit for efiecting energization of oneor the other of said power circuits at all times whereby said reversiblemotor is constantly energized, a holdover circuit connected to saidcontrol circuit operated by operation of said switch in one direction tomaintain the condition eiiected by said control circuit after saidswitch is operated in the opposite direction, and means for periodicallyinterrupting said hold-over circuit to limit the time it holds-thecondition of said control circuit aesasee following the last-mentionedoperation of said switch. "j

3. In a large condition indicating instrument adapted to be stationedout of doors and visible from a substantial distance, in combination, apointer for registering on the instrument dial, a reversible electricmotor for operating said pointer, a switch having movable contacts somei of which are operatively connected to said motor for operationthereby, condition responsive means connected to other of said contactswhereby a variation in the condition moves said lastmentioned contacts,said first-mentioned contacts moving in one direction or another inaccordance with the direction of operation of said motor so that all ofsaid contacts comprise a follow-up device, a control circuit connectedto said switch and accordingly adapted to be made or broken inaccordance with the position of said contacts, a pair of power circuitsfor energizing said motor, a holdover circuit connected to said controlcircuit for maintaining the condition efiected thereby for apredetermined period subsequent to deenergization of said controlcircuit by separation of said contacts, and means under control of saidcontrol and holdover circuits for eflecting energization of one ortheother of said power circuits at all times whereby said electric motor isconstantly energized.

' Juli: W. FRY'MOYER.

